M41T62, M41T64, M41T65 Low-power serial real-time clocks (RTCs) with alarm Datasheet - production data • • • • • • Features • • • • • Serial real-time clock (RTC) with alarm functions 2 − 400 kHz I C serial interface − Memory mapped registers for seconds, minutes, hours, day, date, month, year, and century − Tenths/hundredths of seconds register 350 nA timekeeping current at 3 V Timekeeping down to 1.0 V 2 1.3 V to 4.4 V I C bus operating voltage − 4.4 V max VCC suitable for lithium-ion battery operation Low operating current of 35 µA 2 (at 400 kHz I C speed) August 2015 • • • • 32 KHz square wave output is on at powerup. Suitable for driving a microcontroller in low-power mode. Can be disabled. (M41T62/64) Programmable 1 Hz to 32 KHz square wave output (M41T62/64) Programmable alarm with interrupt function (M41T62/65) 32 KHz crystal oscillator integrates crystal load capacitors, works with high series resistance crystals Oscillator stop detection monitors clock operation Accurate programmable watchdog − 62.5 ms to 31 min timeout Software clock calibration. Can adjust timekeeping to within ±2 parts per million (±5 seconds per month) Automatic leap year compensation –40 to +85 °C operation Two package options − Very small 3 x 3 mm, lead-free & ® halogen-free (ECOPACK2 ) 16-lead QFN − Ultra-small 1.5 x 3.2 mm, lead-free & ® halogen-free (ECOPACK2 ) 8-pin ceramic leadless chip carrier with embedded 32 KHz crystal - no external oscillator components required (M41T62) DocID10397 Rev 21 This is information on a product in full production. 1/45 www.st.com Contents M41T62, M41T64, M41T65 Contents 1 Description....................................................................................... 6 2 Operation ....................................................................................... 11 2.1 3 2-wire bus characteristics ................................................................ 11 2.1.1 Bus not busy ..................................................................................... 11 2.1.2 Start data transfer ............................................................................. 11 2.1.3 Stop data transfer ............................................................................. 11 2.1.4 Data valid .......................................................................................... 12 2.1.5 Acknowledge .................................................................................... 12 2.2 READ mode .................................................................................... 13 2.3 WRITE mode................................................................................... 15 Clock operation ............................................................................. 16 3.1 RTC registers .................................................................................. 17 3.2 Calibrating the clock ........................................................................ 22 3.3 Setting alarm clock registers ........................................................... 24 3.4 Watchdog timer ............................................................................... 25 3.5 Watchdog output (𝐖𝐖𝐖𝐖𝐖𝐖 - M41T65 only) ......................................... 25 3.6 Square wave output (M41T62/64) ................................................... 26 3.7 Full-time 32 KHz square wave output (M41T64) ............................. 26 3.8 Century bits ..................................................................................... 27 3.9 Leap year ........................................................................................ 27 3.10 Output driver pin (M41T62/65) ........................................................ 28 3.11 Oscillator stop detection .................................................................. 28 3.12 Initial power-on defaults .................................................................. 28 4 Maximum ratings ........................................................................... 29 5 DC and AC parameters ................................................................. 30 6 Package information ..................................................................... 34 7 2/45 6.1 QFN16 package information ........................................................... 35 6.2 LCC8 package information .............................................................. 38 Packing information ...................................................................... 40 7.1 QFN16 carrier tape ......................................................................... 40 7.2 LCC8 carrier tape ............................................................................ 41 7.3 Reel information for QFN16 and LCC8 ........................................... 42 DocID10397 Rev 21 M41T62, M41T64, M41T65 Contents 8 Part numbering .............................................................................. 43 9 Revision history ............................................................................ 44 DocID10397 Rev 21 3/45 List of tables M41T62, M41T64, M41T65 List of tables Table 1: Device summary ........................................................................................................................... 6 Table 2: Signal names ................................................................................................................................ 8 Table 3: M41T62 register map.................................................................................................................. 19 Table 4: M41T64 register map.................................................................................................................. 20 Table 5: M41T65 register map.................................................................................................................. 21 Table 6: Alarm repeat modes ................................................................................................................... 24 Table 7: Square wave output frequency ................................................................................................... 26 Table 8: Examples using century bits ....................................................................................................... 27 Table 9: Initial power-up values ................................................................................................................ 28 Table 10: Absolute maximum ratings ....................................................................................................... 29 Table 11: Operating and AC measurement conditions............................................................................. 30 Table 12: Capacitance .............................................................................................................................. 31 Table 13: DC characteristics ..................................................................................................................... 31 Table 14: Crystal electrical characteristics ............................................................................................... 32 Table 15: Crystals suitable for use with M41T6x series RTCs ................................................................. 32 Table 16: Oscillator characteristics ........................................................................................................... 33 Table 17: AC characteristics ..................................................................................................................... 33 Table 18: QFN16 — 16-pin, quad, flat package, no-lead, 3x3 mm, package mechanical data ............... 36 Table 19: LCC8 — 8-pin, 1.5 x 3.2 mm leadless chip carrier package mechanical data ......................... 38 Table 20: Carrier tape dimensions for QFN16 3 x 3 mm package ........................................................... 40 Table 21: Reel dimensions for 12 mm carrier tape - QFN16 and LCC8 packages .................................. 42 Table 22: Ordering information scheme ................................................................................................... 43 Table 23: Document revision history ........................................................................................................ 44 4/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 List of figures List of figures Figure 1: M41T62 logic diagram ................................................................................................................. 6 Figure 2: M41T64 logic diagram ................................................................................................................. 7 Figure 3: M41T65 logic diagram ................................................................................................................. 7 Figure 4: M41T62 connections ................................................................................................................... 7 Figure 5: M41T64 connections ................................................................................................................... 8 Figure 6: M41T65 connections ................................................................................................................... 8 Figure 7: M41T62 block diagram ................................................................................................................ 9 Figure 8: M41T64 block diagram ................................................................................................................ 9 Figure 9: M41T65 block diagram ................................................................................................................ 9 Figure 10: Hardware hookup for SuperCap™ backup operation ............................................................. 10 Figure 11: Serial bus data transfer sequence ........................................................................................... 12 Figure 12: Acknowledgement sequence................................................................................................... 13 Figure 13: Slave address location ............................................................................................................ 13 Figure 14: READ mode sequence ............................................................................................................ 14 Figure 15: Alternative READ mode sequence .......................................................................................... 14 Figure 16: WRITE mode sequence .......................................................................................................... 15 Figure 17: Buffer/transfer registers ........................................................................................................... 17 Figure 18: Crystal accuracy across temperature ...................................................................................... 23 Figure 19: Calibration waveform ............................................................................................................... 23 Figure 20: Alarm interrupt reset waveform ............................................................................................... 24 Figure 21: Century bits CB1 and CB0 ...................................................................................................... 27 Figure 22: AC measurement I/O waveform .............................................................................................. 30 Figure 23: Crystal isolation example......................................................................................................... 30 Figure 24: Bus timing requirements sequence ......................................................................................... 33 Figure 25: QFN16 — 16-pin, quad, flat package, no-lead, 3x3 mm, package outline ............................. 35 Figure 26: QFN16 — 16-pin, quad, flat package, no-lead, 3 x 3 mm recommended footprint................. 37 Figure 27: LCC8 — 8-pin, 1.5 x 3.2 mm leadless chip carrier package outline ....................................... 38 Figure 28: LCC8 — 8-pin, 1.5 x 3.2 mm leadless chip carrier recommended footprint ........................... 39 Figure 29: Carrier tape for QFN16 3 x 3 mm package ............................................................................. 40 Figure 30: Carrier tape for LCC8 1.5 x 3.2 mm package.......................................................................... 41 Figure 31: Reel schematic ........................................................................................................................ 42 DocID10397 Rev 21 5/45 Description 1 M41T62, M41T64, M41T65 Description The M41T6x is a low-power serial real-time clock (RTC) with a built-in 32.768 kHz oscillator. Eight registers are used for the clock/calendar function and are configured in binary-coded decimal (BCD) format. An additional eight registers provide status/control of alarm, 32 KHz output, calibration, and watchdog functions. Addresses and data are 2 transferred serially via a two-line, bidirectional I C interface. The built-in address register is incremented automatically after each WRITE or READ data byte. Functions available to the user include a time-of-day clock/calendar, alarm interrupts (M41T62/65), 32 KHz output (M41T62/64), programmable square wave output (M41T62/64), and watchdog output (M41T65). The eight clock address locations contain the century, year, month, date, day, hour, minute, second and tenths/hundredths of a second in 24-hour BCD format. Corrections for 28-, 29- (leap year), 30- and 31-day months are made automatically. The M41T6x is supplied in two very small packages: a tiny, 3 x 3 mm 16-pin QFN which requires a user-supplied 32 KHz crystal, and an ultra-small 1.5 x 3.2 mm LCC with embedded crystal - no external crystal is required. Table 1: Device summary Device Basic RTC Alarms OSC fail detect Watchdog timer Calibration SQW output M41T62 ✓ ✓ ✓ ✓ ✓ ✓ M41T64 ✓ ✓ ✓ ✓ ✓ ✓ M41T65 ✓ ✓ ✓ ✓ ✓ ✓ ✓ VCC (3) XI (3) SCL (1) M41T62 SDA VSS 1. 2. 3. 6/45 IRQ/OUT (2) SQW Open drain. Defaults to 32 KHz on power-up. Not bonded on LCC package. DocID10397 Rev 21 𝐖𝐖𝐖𝐖𝐖𝐖 output F32K output ✓ Figure 1: M41T62 logic diagram XO 𝐈𝐈𝐈𝐈𝐐𝐐 output ✓ M41T62, M41T64, M41T65 Description Figure 2: M41T64 logic diagram VCC XI (1) XO SQW M41T64 SCL (2) F32K SDA VSS 1. 2. Open drain. Defaults to 32 KHz on power-up. Figure 3: M41T65 logic diagram VCC XI WDO(1) XO M41T65 SCL (1) IRQ/FT/OUT SDA VSS 1. Open drain. 1. 2. NC NC VCC NC Figure 4: M41T62 connections 16 15 14 13 VSS NC NC 5 VCC LCC 8 NC 7 4 NC 9 6 IRQ/OUT(2) SDA 4 5 6 VSS 10 SQW(1) 3 SCL 3 VSS QFN NC 2 IRQ/OUT(2) 2 7 SQW(1) 11 XO SCL 1 NC 1 8 SDA 12 XI SQW output defaults to 32 KHz upon power-up. Open drain. DocID10397 Rev 21 7/45 Description M41T62, M41T64, M41T65 NC NC VCC NC Figure 5: M41T64 connections 16 15 14 13 XI 1 12 NC XO 2 11 SQW(2) VSS 3 10 SCL (1) 4 9 SDA 1. 2. 7 8 NC 6 NC VSS 5 NC F32K Enabled on power-up. Open drain. 1. NC NC VCC NC Figure 6: M41T65 connections 16 15 14 13 XO 2 11 IRQ/FT/OUT(1) VSS 3 10 SCL WDO(1) 4 9 SDA 5 6 7 8 NC NC NC 12 NC 1 VSS XI Open drain. Table 2: Signal names XI Oscillator input XO Oscillator output SDA Serial data input/output SCL Serial clock input IRQ/OUT IRQ/FT/OUT 8/45 Interrupt or OUT output (open drain) Interrupt, frequency test, or OUT output (open drain) SQW Programmable square wave - defaults to 32 KHz on power-up (open drain for M41T64 only) F32K Dedicated 32 KHz output (M41T64 only) WDO Watchdog timer output (open drain) VCC Supply voltage VSS Ground DocID10397 Rev 21 M41T62, M41T64, M41T65 Description Figure 7: M41T62 block diagram REAL TIME CLOCK CALENDAR (3) XTAL (3) SDA 32KHz OSCILLATOR I2C INTERFACE SCL 1. 2. 3. OSCILLATOR FAIL DETECT OFIE RTC W/ALARM AFE IRQ/OUT(1) SQWE SQW(2) WATCHDOG SQUARE WAVE Open drain. Defaults to 32 KHz on power-up. Not bonded on embedded crystal (LCC) package. Figure 8: M41T64 block diagram 32KE REAL TIME CLOCK CALENDAR XTAL (1) F32K OSCILLATOR FAIL DETECT 32KHz OSCILLATOR RTC W/ALARM SDA WATCHDOG I2C INTERFACE 1. 2. SQWE SQUARE WAVE SCL (2) SQW Defaults enabled on power-up. Open drain. Figure 9: M41T65 block diagram REAL TIME CLOCK CALENDAR XTAL 32KHz OSCILLATOR OSCILLATOR FAIL OFIE DETECT FT RTC W/ALARM SDA I2C INTERFACE WATCHDOG AFE IRQ/FT/OUT WDO (1) (1) SCL 1. Open drain. DocID10397 Rev 21 9/45 Description M41T62, M41T64, M41T65 Figure 10: Hardware hookup for SuperCap™ backup operation POWER SUPPLY VCC (1) D1 + – Ro LEAKAGE� PATH M41T6x VCC XI XO (2) IRQ/FT/OUT (3) WDO (4) SQW VSS 1. 2. 3. 4. D2 MCU VCC Port Reset Input SQWIN SCL Serial Clock Line SDA Serial Data Line F32K 32KHz CLKIN Diode D2 required on open drain pin (M41T65 only) when using SuperCap (or battery) backup. Low threshold BAT42 schottky diode recommended (see note below). D1 and D2 should be of the same type. For M41T62 and M41T65 (open drain). For M41T65 (open drain). For M41T64 (open drain). Note: Some power supplies, when shut off, can present a leakage path to ground which will shorten the backup time provided by the SuperCap (or battery). In such cases, a very low leakage diode is recommended for D1 (and D2). A non-schottky such as the 1N4148 will have very low reverse leakage. 10/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 2 Operation Operation The M41T6x clock operates as a slave device on the serial bus. Access is obtained by implementing a start condition followed by the correct slave address (D0h). The 16 bytes contained in the device can then be accessed sequentially in the following order: • • • • • • • • • • • • 2.1 st 1 byte: tenths/hundredths of a second register nd 2 byte: seconds register rd 3 byte: minutes register th 4 byte: hours register th 5 byte: square wave/day register th 6 byte: date register th 7 byte: century/month register th 8 byte: year register th 9 byte: calibration register th 10 byte: watchdog register th th 11 - 15 bytes: alarm registers th 16 byte: flags register 2-wire bus characteristics The bus is intended for communication between different ICs. It consists of two lines: a bidirectional data signal (SDA) and a clock signal (SCL). Both the SDA and SCL lines must be connected to a positive supply voltage via a pull-up resistor. The following protocol has been defined: • • • Data transfer may be initiated only when the bus is not busy. During data transfer, the data line must remain stable whenever the clock line is high. Changes in the data line, while the clock line is high, will be interpreted as control signals. Accordingly, the following bus conditions have been defined. 2.1.1 Bus not busy Both data and clock lines remain high. 2.1.2 Start data transfer A change in the state of the data line, from high to low, while the clock is high, defines the START condition. 2.1.3 Stop data transfer A change in the state of the data line, from low to high, while the clock is high, defines the STOP condition. DocID10397 Rev 21 11/45 Operation 2.1.4 M41T62, M41T64, M41T65 Data valid The state of the data line represents valid data when after a start condition, the data line is stable for the duration of the high period of the clock signal. The data on the line may be changed during the Low period of the clock signal. There is one clock pulse per bit of data. Each data transfer is initiated with a start condition and terminated with a stop condition. The number of data bytes transferred between the start and stop conditions is not limited. The information is transmitted byte-wide and each receiver acknowledges with a ninth bit. By definition a device that gives out a message is called “transmitter,” the receiving device that gets the message is called “receiver.” The device that controls the message is called “master.” The devices that are controlled by the master are called “slaves.” 2.1.5 Acknowledge Each byte of eight bits is followed by one acknowledge bit. This acknowledge bit is a low level put on the bus by the receiver whereas the master generates an extra acknowledge related clock pulse. A slave receiver which is addressed is obliged to generate an acknowledge after the reception of each byte that has been clocked out of the slave transmitter. The device that acknowledges has to pull down the SDA line during the acknowledge clock pulse in such a way that the SDA line is a stable Low during the high period of the acknowledge related clock pulse. Of course, setup and hold times must be taken into account. A master receiver must signal an end of data to the slave transmitter by not generating an acknowledge on the last byte that has been clocked out of the slave. In this case the transmitter must leave the data line high to enable the master to generate the STOP condition. Figure 11: Serial bus data transfer sequence DATA LINE STABLE DATA VALID CLOCK DATA START CONDITION 12/45 CHANGE OF DATA ALLOWED DocID10397 Rev 21 STOP CONDITION M41T62, M41T64, M41T65 Operation Figure 12: Acknowledgement sequence CLOCK PULSE FOR ACKNOWLEDGEMENT START SCL FROM MASTER 1 DATA OUTPUT BY TRANSMITTER 2 8 MSB 9 LSB DATA OUTPUT BY RECEIVER READ mode In this mode the master reads the M41T6x slave after setting the slave address (see Figure 14: "READ mode sequence"). Following the WRITE mode control bit (R/W̅ =0) and the acknowledge bit, the word address 'An' is written to the on-chip address pointer. Next the START condition and slave address are repeated followed by the READ mode control bit (R/W̅ =1). At this point the master transmitter becomes the master receiver. The data byte which was addressed will be transmitted and the master receiver will send an acknowledge bit to the slave transmitter. the address pointer is only incremented on reception of an acknowledge clock. The M41T6x slave transmitter will now place the data byte at address An+1 on the bus, the master receiver reads and acknowledges the new byte and the address pointer is incremented to “An+2.” This cycle of reading consecutive addresses will continue until the master receiver sends a STOP condition to the slave transmitter. The system-to-user transfer of clock data will be halted whenever the address being read is a clock address (00h to 07h). The update will resume due to a stop condition or when the pointer increments to any non-clock address (08h-0Fh). Note: This is true both in READ mode and WRITE mode. An alternate READ mode may also be implemented whereby the master reads the M41T6x slave without first writing to the (volatile) address pointer. The first address that is read is the last one stored in the pointer (see Figure 15: "Alternative READ mode sequence"). Figure 13: Slave address location R/W SLAVE ADDRESS START A 1 LSB MSB 2.2 1 0 1 0 0 DocID10397 Rev 21 0 13/45 Operation M41T62, M41T64, M41T65 DATA n DATA n+1 ACK ACK S ACK BUS ACTIVIT Y: R/W START WORD ADDRESS (An) ACK S R/W SDA LINE ACK BUS ACTIVIT Y: MASTER START Figure 14: READ mode sequence SLAVE ADDRESS STOP SLAVE ADDRESS P NO ACK DATA n+X STOP SL AVE ADDRESS 14/45 DocID10397 Rev 21 P NO ACK DATA n+X ACK BUS ACTIVIT Y: DATA n+1 ACK DATA n ACK S ACK SD A LINE R/W BUS ACTIVIT Y: MASTER START Figure 15: Alternative READ mode sequence M41T62, M41T64, M41T65 WRITE mode In this mode the master transmitter transmits to the M41T6x slave receiver. Bus protocol is shown in Figure 16: "WRITE mode sequence". Following the START condition and slave address, a logic '0' (R/W̅ =0) is placed on the bus and indicates to the addressed device that word address “An” will follow and is to be written to the on-chip address pointer. The data word to be written to the memory is strobed in next and the internal address pointer is incremented to the next address location on the reception of an acknowledge clock. The M41T6x slave receiver will send an acknowledge clock to the master transmitter after it has received the slave address see Figure 13: "Slave address location" and again after it has received the word address and each data byte. DATA n+X P ACK DATA n+1 ACK BUS ACTIVIT Y: DATA n ACK WORD ADDRESS (An) ACK S R/W SD A LINE ACK BUS ACTIVIT Y: MASTER STOP Figure 16: WRITE mode sequence START 2.3 Operation SL AVE ADDRESS DocID10397 Rev 21 15/45 Clock operation 3 M41T62, M41T64, M41T65 Clock operation The M41T6x is driven by a quartz-controlled oscillator with a nominal frequency of 32.768 kHz. The accuracy of the real-time clock depends on the frequency of the quartz crystal that is used as the time-base for the RTC. The eight byte clock register (see Table 3: "M41T62 register map", Table 4: "M41T64 register map", and Table 5: "M41T65 register map") is used to both set the clock and to read the date and time from the clock, in a binary-coded decimal format. Tenths/hundredths of seconds, seconds, minutes, and hours are contained within the first four registers. A WRITE to any clock register will result in the tenths/hundredths of seconds being reset to “00,” and tenths/hundredths of seconds cannot be written to any value other than “00.” Bits D0 through D2 of register 04h contain the day (day of week). Registers 05h, 06h, and 07h contain the date (day of month), month, and years. The ninth clock register is the calibration register (this is described in the clock calibration section). Bit D7 of register 01h contains the STOP bit (ST). Setting this bit to a '1' will cause the oscillator to stop. When reset to a '0' the oscillator restarts within one second (typical). Upon initial power-up, the user should set the ST bit to a '1,' then immediately reset the ST bit to '0.' This provides an additional “kick-start” to the oscillator circuit. Bit D7 of register 02h (minute register) contains the oscillator fail interrupt enable bit (OFIE). When the user sets this bit to '1,' any condition which sets the oscillator fail bit (OF) (see Section 3.11: "Oscillator stop detection") will also generate an interrupt output. Bits D6 and D7 of clock register 06h (century/month register) contain the CENTURY bit 0 (CB0) and CENTURY bit 1 (CB1). A WRITE to ANY location within the first eight bytes of the clock register (00h-07h), including the OFIE bit, RS0-RS3 bit, and CB0-CB1 bits will result in an update of the system clock and a reset of the divider chain. This could result in an inadvertent change of the current time. These non-clock related bits should be written prior to setting the clock, and remain unchanged until such time as a new clock time is also written. The eight clock registers may be read one byte at a time, or in a sequential block. Provision has been made to assure that a clock update does not occur while any of the eight clock addresses are being read. If a clock address is being read, an update of the clock registers will be halted. This will prevent a transition of data during the READ. 16/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 3.1 Clock operation RTC registers The M41T6x user interface is comprised of 16 memory mapped registers which include clock, calibration, alarm, watchdog, flags, and square wave control. The eight clock counters are accessed indirectly via a set of buffer/transfer registers while the other eight registers are directly accessed. Data in the clock and alarm registers is in BCD format. Figure 17: Buffer/transfer registers Updates During normal operation when the user is not accessing the device, the buffer/transfer 2 registers are kept updated with a copy of the RTC counters. At the start of an I C read or write cycle, the updating is halted and the present time is frozen in the buffer/transfer registers. Reads of the clock registers 2 By halting the updates at the start of an I C access, the user is ensured that all the data transferred out during a read sequence comes from the same instant in time. DocID10397 Rev 21 17/45 Clock operation M41T62, M41T64, M41T65 Write timing 2 When writing to the device, the data is shifted into the M41T62's I C interface on the rising edge of the SCL signal. As shown in Figure 17: "Buffer/transfer registers", on the 8th clock 2 cycle, the data is transferred from the I C block into whichever register is being pointed to by the address pointer (not shown). Writes to the clock registers (addresses 0-7) Data written to the clock registers (addresses 0-7) is held in the buffer registers until the 2 address pointer increments to 8, or an I C stop condition occurs, at which time the data in the buffer/registers is simultaneously copied into the counters, and then the clock is restarted. 18/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 Clock operation Table 3: M41T62 register map Addr D7 00h D6 D5 D4 D3 D2 0.1 seconds D1 D0 Function/range BCD format 0.01 seconds 10ths/100ths of seconds 00-99 01h ST 10 seconds Seconds Seconds 00-59 02h OFIE 10 minutes Minutes Minutes 00-59 03h 0 0 Hours (24-hour format) Hours 00-23 04h RS3 RS2 Day 01-7 05h 0 0 Date: day of month Date 01-31 06h CB1 CB0 Month Century/ month 0-3/01-12 Year Year 00-99 07h 10 hours RS1 RS0 0 Day of week 10 date 0 10M 10 years 08h OUT 0 S Calibration 09h RB2 BMB4 BMB3 BMB2 0Ah AFE SQWE 0 Al 10M 0Bh RPT4 RPT5 0Ch RPT3 0 0Dh RPT2 0Eh RPT1 0Fh WDF BMB1 BMB0 Calibration RB1 RB0 Watchdog Alarm month Al month 01-12 AI 10 date Alarm date Al date 01-31 AI 10 hour Alarm hour Al hour 00-23 Alarm 10 minutes Alarm minutes Al min 00-59 Alarm 10 seconds Alarm seconds Al sec 00-59 AF 0 0 0 OF 0 0 Flags Keys: 0 = must be set to '0' AF = alarm flag (read only) AFE = alarm flag enable flag BMB0 - BMB4 = watchdog multiplier bits CB0-CB1 = century bits OF = oscillator fail bit OFIE = oscillator fail interrupt enable bit OUT = output level RB0 - RB2 = watchdog resolution bits RPT1-RPT5 = alarm repeat mode bits RS0-RS3 = SQW frequency bits S = sign bit SQWE = square wave enable bit ST = stop bit WDF = watchdog flag bit (read only) DocID10397 Rev 21 19/45 Clock operation M41T62, M41T64, M41T65 Table 4: M41T64 register map Addr D7 00h D6 D5 D4 D3 D2 0.1 seconds D0 Function/range BCD format 0.01 seconds 10ths/100ths of seconds 00-99 01h ST 10 seconds Seconds Seconds 00-59 02h 0 10 minutes Minutes Minutes 00-59 03h 0 0 Hours (24-hour format) Hours 00-23 04h RS3 RS2 Day 01-7 05h 0 0 Date: day of month Date 01-31 06h CB1 CB0 Month Century/ month 0-3/01-12 Year Year 00-99 07h 10 hours RS1 RS0 0 Day of week 10 Date 0 10M 10 years 08h 0 0 S Calibration 09h RB2 BMB4 BMB3 BMB2 0Ah 0 SQWE 32KE Al 10M 0Bh RPT4 RPT5 0Ch RPT3 0 0Dh RPT2 0Eh RPT1 0Fh WDF BMB1 BMB0 Calibration RB1 RB0 Watchdog Alarm month Al month 01-12 AI 10 date Alarm date Al date 01-31 AI 10 hour Alarm hour Al hour 00-23 Alarm 10 minutes Alarm minutes Al min 00-59 Alarm 10 seconds Alarm seconds Al sec 00-59 AF 0 0 0 OF Keys: 0 = must be set to '0' 32KE = 32 KHz enable bit AF = alarm flag (read only) BMB0 - BMB4 = watchdog multiplier bits CB0-CB1 = century bits OF = oscillator fail bit RB0 - RB2 = watchdog resolution bits RPT1-RPT5 = alarm repeat mode bits RS0-RS3 = SQW frequency bits S = sign bit SQWE = square wave enable bit ST = stop bit WDF = watchdog flag bit (read only) 20/45 D1 DocID10397 Rev 21 0 0 Flags M41T62, M41T64, M41T65 Clock operation Table 5: M41T65 register map Addr D7 00h D6 D5 D4 D3 D2 0.1 seconds D1 D0 Function/range BCD format 0.01 seconds 10ths/100ths of seconds 00-99 01h ST 10 seconds Seconds Seconds 00-59 02h OFIE 10 minutes Minutes Minutes 00-59 03h 0 0 Hours (24-hour format) Hours 00-23 04h 0 0 Day 01-7 05h 0 0 Date: day of month Date 01-31 06h CB1 CB0 Month Century/ month 0-3/01-12 Year Year 00-99 07h 10 hours 0 0 0 10 date 0 Day of week 10M 10 years 08h OUT FT S Calibration 09h RB2 BMB4 BMB3 BMB2 0Ah AFE 0 0 Al 10M 0Bh RPT4 RPT5 0Ch RPT3 0 0Dh RPT2 0Eh RPT1 0Fh WDF BMB1 BMB0 Calibration RB1 RB0 Watchdog Alarm month Al month 01-12 AI 10 date Alarm date Al date 01-31 AI 10 hour Alarm hour Al hour 00-23 Alarm 10 minutes Alarm minutes Al min 00-59 Alarm 10 seconds Alarm seconds Al sec 00-59 AF 0 0 0 OF 0 0 Flags Keys: 0 = must be set to '0' AF = alarm flag (read only) AFE = alarm flag enable flag BMB0 - BMB4 = watchdog multiplier bits CB0-CB1 = century bits FT = frequency test bit OF = oscillator fail bit OFIE = oscillator fail interrupt enable bit OUT = output level RB0 - RB2 = watchdog resolution bits RPT1-RPT5 = alarm repeat mode bits S = sign bit ST = stop bit WDF = watchdog flag bit (read only) DocID10397 Rev 21 21/45 Clock operation 3.2 M41T62, M41T64, M41T65 Calibrating the clock The M41T6x real-time clock is driven by a quartz controlled oscillator with a nominal frequency of 32,768 Hz. This provides the time-base for the RTC. The accuracy of the clock depends on the frequency accuracy of the crystal, and the match between the capacitive load of the oscillator circuit and the capacitive load for which the crystal was trimmed. The M41T6x oscillator is designed for use with a 6 - 7 pF crystal load capacitance. When the calibration circuit is properly employed, accuracy improves to better than ±2 ppm at 25 °C. The oscillation rate of crystals changes with temperature (see Figure 18: "Crystal accuracy across temperature"). Therefore, the M41T6x design employs periodic counter correction. The calibration circuit adds or subtracts counts from the oscillator divider circuit at the divide by 256 stage, as shown in Figure 19: "Calibration waveform". The number of times pulses which are blanked (subtracted, negative calibration) or split (added, positive calibration) depends upon the value loaded into the five calibration bits found in the calibration register. Adding counts speeds the clock up, subtracting counts slows the clock down. The calibration bits occupy the five lower order bits (D4-D0) in the calibration register (08h). These bits can be set to represent any value between 0 and 31 in binary form. Bit D5 is a sign bit; '1' indicates positive calibration, '0' indicates negative calibration. Calibration occurs within a 64 minute cycle. The first 62 minutes in the cycle may, once per minute, have one second either shortened by 128 or lengthened by 256 oscillator cycles. If a binary '1' is loaded into the register, only the first 2 minutes in the 64 minute cycle will be modified; if a binary 6 is loaded, the first 12 will be affected, and so on. Therefore, each calibration step has the effect of adding 512 or subtracting 256 oscillator cycles for every 125,829,120 actual oscillator cycles, that is +4.068 or –2.034 ppm of adjustment per calibration step in the calibration register. Assuming that the oscillator is running at exactly 32,768 Hz, each of the 31 increments in the calibration byte would represent +10.7 or –5.35 seconds per day which corresponds to a total range of +5.5 or –2.75 minutes per month (see Figure 19: "Calibration waveform"). Two methods are available for ascertaining how much calibration a given M41T6x may require: • • The first involves setting the clock, letting it run for a month and comparing it to a known accurate reference and recording deviation over a fixed period of time. Calibration values, including the number of seconds lost or gained in a given period, can be found in application note AN934. This allows the designer to give the end user the ability to calibrate the clock as the environment requires, even if the final product is packaged in a non-user serviceable enclosure. The designer could provide a simple utility that accesses the calibration byte. The second approach is better suited to a manufacturing environment, and involves the use of either the SQW pin (M41T62/64) or the IRQ/FT/OUT pin (M41T65). The SQW pin will toggle at 512 Hz when RS3 = '0,' RS2 = '1,' RS1 = '1,' RS0 = '0,' SQWE = '1,' and ST = '0.' Alternatively, for the M41T65, the IRQ/FT/OUT pin will toggle at 512 Hz when FT and OUT bits = '1' and ST = '0.' Any deviation from 512 Hz indicates the degree and direction of oscillator frequency shift at the test temperature. For example, a reading of 512.010124 Hz would indicate a +20 ppm oscillator frequency error, requiring a –10 (XX001010) to be loaded into the calibration byte for correction. Note that setting or changing the calibration byte does not affect the frequency test or square wave output frequency. 22/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 Clock operation Figure 18: Crystal accuracy across temperature Frequency (ppm) 20 0 –20 –40 –60 ∆F = K x (T – T )2 O F –80 2 2 K = –0.036 ppm/°C ± 0.006 ppm/°C –100 TO = 25°C ± 5°C –120 –140 –160 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 Temperature °C Figure 19: Calibration waveform NORMAL POSITIVE CALIBRATION NEGATIVE CALIBRATION DocID10397 Rev 21 23/45 Clock operation 3.3 M41T62, M41T64, M41T65 Setting alarm clock registers Address locations 0Ah-0Eh contain the alarm settings. The alarm can be configured to go off at a prescribed time on a specific month, date, hour, minute, or second, or repeat every year, month, day, hour, minute, or second. Bits RPT5–RPT1 put the alarm in the repeat mode of operation. Table 6: "Alarm repeat modes" shows the possible configurations. Codes not listed in the table default to the once per second mode to quickly alert the user of an incorrect alarm setting. When the clock information matches the alarm clock settings based on the match criteria defined by RPT5–RPT1, the AF (alarm flag) is set. If AFE (alarm flag enable) is also set (M41T62/65), the alarm condition activates the IRQ/OUT or IRQ/FT/OUT pin. To disable the alarm, write '0' to the alarm date register and to RPT5–RPT1. Note: If the address pointer is allowed to increment to the flag register address, an alarm condition will not cause the interrupt/flag to occur until the address pointer is moved to a different address. It should also be noted that if the last address written is the “Alarm Seconds,” the address pointer will increment to the flag address, causing this situation to occur. The IRQ output is cleared by a READ to the flags register as shown in Figure 20: "Alarm interrupt reset waveform". A subsequent READ of the flags register is necessary to see that the value of the alarm flag has been reset to '0.' Figure 20: Alarm interrupt reset waveform 0Eh Register address 00h 0Fh ALARM FLAG BIT (AF) HIGH-Z IRQ/OUT or IRQ/FT/OUT Table 6: Alarm repeat modes 24/45 RPT5 RPT4 RPT3 RPT2 RPT1 Alarm setting 1 1 1 1 1 Once per second 1 1 1 1 0 Once per minute 1 1 1 0 0 Once per hour 1 1 0 0 0 Once per day 1 0 0 0 0 Once per month 0 0 0 0 0 Once per year DocID10397 Rev 21 M41T62, M41T64, M41T65 3.4 Clock operation Watchdog timer The watchdog timer can be used to detect an out-of-control microprocessor. The user programs the watchdog timer by setting the desired amount of time-out into the watchdog register, address 09h. Bits BMB4-BMB0 store a binary multiplier and the three bits RB2-RB0 select the resolution where: 000=1/16 second (16 Hz); 001=1/4 second (4 Hz); 010=1 second (1 Hz); 011=4 seconds (1/4 Hz); and 100 = 1 minute (1/60 Hz). Note: Invalid combinations (101, 110, and 111) will NOT enable a watchdog time-out. Setting BMB4-BMB0 = 00000 with any combination of RB2-RB0, other than 000, will result in an immediate watchdog time-out. The amount of time-out is then determined to be the multiplication of the five-bit multiplier value with the resolution. (For example: writing 00001110 in the watchdog register = 3*1 or 3 seconds). If the processor does not reset the timer within the specified period, the M41T6x sets the WDF (watchdog flag) and generates an interrupt on the IRQ pin (M41T62), or a watchdog output pulse (M41T65 only) on the WDO pin. The watchdog timer can only be reset by having the microprocessor perform a WRITE of the watchdog register. The time-out period then starts over. Should the watchdog timer time-out, any value may be written to the watchdog register in order to clear the IRQ pin. A value of 00h will disable the watchdog function until it is again programmed to a new value. A READ of the flags register will reset the watchdog flag (bit D7; register 0Fh). The watchdog function is automatically disabled upon power-up, and the watchdog register is cleared. Note: A WRITE to any clock register will restart the watchdog timer. 3.5 Watchdog output (𝐖𝐖𝐖𝐖𝐖𝐖 - M41T65 only) If the processor does not reset the watchdog timer within the specified period, the watchdog output (WDO) will pulse low for trec (see Table 7: "Square wave output frequency"). This output may be connected to the reset input of the processor in order to generate a processor reset. After a watchdog time-out occurs, the timer will remain disabled until such time as a new countdown value is written into the watchdog register. Note: The crystal oscillator must be running for the 𝑊𝑊𝑊𝑊𝑊𝑊 pulse to be available. The 𝑊𝑊𝑊𝑊𝑊𝑊 output is an N-channel, open drain output driver (with IOL as specified in Table 13: "DC characteristics"). DocID10397 Rev 21 25/45 Clock operation 3.6 M41T62, M41T64, M41T65 Square wave output (M41T62/64) The M41T62/64 offers the user a programmable square wave function which is output on the SQW pin. RS3-RS0 bits located in 04h establish the square wave output frequency. These frequencies are listed in Table 7: "Square wave output frequency". Once the selection of the SQW frequency has been completed, the SQW pin can be turned on and off under software control with the square wave enable bit (SQWE) located in register 0Ah. The SQW output is an N-channel, open drain output driver for the M41T64, and a full CMOS output driver for the M41T62. The initial power-up default for the SQW output is 32 KHz (except for M41T64, which defaults disabled). Table 7: Square wave output frequency Square wave bits 3.7 Square wave RS3 RS2 RS1 RS0 Frequency Units 0 0 0 0 None – 0 0 0 1 32.768 kHz 0 0 1 0 8.192 kHz 0 0 1 1 4.096 kHz 0 1 0 0 2.048 kHz 0 1 0 1 1.024 kHz 0 1 1 0 512 Hz 0 1 1 1 256 Hz 1 0 0 0 128 Hz 1 0 0 1 64 Hz 1 0 1 0 32 Hz 1 0 1 1 16 Hz 1 1 0 0 8 Hz 1 1 0 1 4 Hz 1 1 1 0 2 Hz 1 1 1 1 1 Hz Full-time 32 KHz square wave output (M41T64) The M41T64 offers the user a special 32 KHz square wave function which is enabled on power-up to output on the F32K pin as long as VCC ≥ 1.3 V, and the oscillator is running (ST bit = '0'). This function is available within one second (typ) of initial power-up and can only be disabled by setting the 32KE bit to '0' or the ST bit to '1.' If not used, the F32K pin should be disconnected and allowed to float. 26/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 3.8 Clock operation Century bits The two century bits, CB1 and CB0, are bits D7 and D6, respectively, in the century/month register at address 06h. Together, they comprise a 2-bit counter which increments at the turn of each century. CB1 is the most significant bit. The user may arbitrarily assign the meaning of CB1:CB0 to represent any century value, but the simplest way of using these bits is to extend the year register (07h) by mapping them directly to bits 9 and 8. (The reader is reminded that the year register is in BCD format.) Higher order year bits can be maintained in the application software. Figure 21: Century bits CB1 and CB0 Table 8: Examples using century bits 3.9 CB1 CB0 CENTURY 0 0 2000 0 1 2100 1 0 2200 1 1 2300 Leap year Leap year occurs every four years, in years which are multiples of 4. For example, 2012 was a leap year. An exception to that is any year which is a multiple of 100. For example, the year 2100 is not a leap year. A further exception is that years which are multiples of 400 are indeed leap years. Hence, while 2100 is not a leap year, 2400 is. During any year which is a multiple of 4, the M41T6x RTC will automatically insert leap day, February 29. Therefore, the application software must correct for this during the exception years (2100, 2200, etc.) as noted above. DocID10397 Rev 21 27/45 Clock operation 3.10 M41T62, M41T64, M41T65 Output driver pin (M41T62/65) When the OFIE bit, AFE bit, and watchdog register are not set to generate an interrupt, the IRQ/OUT pin becomes an output driver that reflects the contents of D7 of the calibration register. In other words, when D7 (OUT bit) is a '0,' then the IRQ/OUT pin will be driven low. 3.11 Note: The 𝐼𝐼𝐼𝐼𝐼𝐼/OUT pin is an open drain which requires an external pull-up resistor. Oscillator stop detection If the oscillator fail (OF) bit is internally set to a '1,' this indicates that the oscillator has either stopped, or was stopped for some period of time and can be used to judge the validity of the clock and date data. This bit will be set to '1' any time the oscillator stops. In the event the OF bit is found to be set to '1' at any time other than the initial power-up, the STOP bit (ST) should be written to a '1,' then immediately reset to '0.' This will restart the oscillator. The following conditions can cause the OF bit to be set: • The first time power is applied (defaults to a '1' on power-up). Note: If the OF bit cannot be written to '0' four (4) seconds after the initial power-up, the STOP bit (ST) should be written to a '1,' then immediately reset to '0.' • • • The voltage present on VCC or battery is insufficient to support oscillation. The ST bit is set to '1.' External interference of the crystal If the oscillator fail interrupt enable bit (OFIE) is set to a '1,' the IRQ pin will also be activated. The IRQ output is cleared by resetting the OFIE or OF bit to '0' (NOT by reading the flag register). The OF bit will remain set to '1' until written to logic '0.' The oscillator must start and have run for at least 4 seconds before attempting to reset the OF bit to '0.' If the trigger event occurs during a power-down condition, this bit will be set correctly. 3.12 Initial power-on defaults Upon application of power to the device, the register bits will initially power-on in the state indicated in Table 9: "Initial power-up values". Table 9: Initial power-up values Condition Initial (1) power-up Device ST OF OFIE OUT FT AFE SQWE 32KE RS3-1 RS0 Watchdog M41T62 0 1 0 1 N/A 0 1 N/A 0 1 0 M41T64 0 1 N/A N/A N/A N/A 0 1 0 1 0 M41T65 0 1 0 1 0 0 N/A N/A N/A N/A 0 Notes: (1) All other control bits power up in an undetermined state. 28/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 4 Maximum ratings Maximum ratings Stressing the device above the rating listed in the absolute maximum ratings table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 10: Absolute maximum ratings TSTG Storage temperature (VCC off, oscillator off) –55 to 125 Supply voltage –0.3 to 5.0 V 260 °C –0.2 to Vcc+0.3 V VCC (3) Lead solder temperature for 10 seconds Value (2) Parameter TSLD Condition (1) Sym Unit °C VIO Input or output voltages IO Output current 20 mA PD Power dissipation 1 W VESD(HBM) Electro-static discharge voltage (human body model) TA = 25 °C >1500 V VESD(RCDM) Electro-static discharge voltage (robotic charged device model) TA = 25 °C >1000 V Notes: (1) (2) (3) Test conforms to JEDEC standard. Data based on characterization results, not tested in production. Reflow at peak temperature of 260 °C. The time above 255 °C must not exceed 30 seconds. DocID10397 Rev 21 29/45 DC and AC parameters 5 M41T62, M41T64, M41T65 DC and AC parameters This section summarizes the operating and measurement conditions, as well as the DC and AC characteristics of the device. The parameters in the following DC and AC characteristic tables are derived from tests performed under the measurement conditions listed in the relevant tables. Designers should check that the operating conditions in their projects match the measurement conditions when using the quoted parameters. Table 11: Operating and AC measurement conditions Parameter M41T6x Supply voltage (VCC) 1.3 V to 4.4 V Ambient operating temperature (TA) –40 to 85 °C Load capacitance (CL) 50 pF Input rise and fall times ≤ 5 ns Input pulse voltages 0.2 VCC to 0.8 VCC Input and output timing ref. voltages 0.3 VCC to 0.7 VCC Note: Output Hi-Z is defined as the point where data is no longer driven. Figure 22: AC measurement I/O waveform 0.8VCC 0.7VCC 0.3VCC 0.2VCC Figure 23: Crystal isolation example Local Grounding Plane (Layer 2) Crystal XI XO GND Note: Substrate pad should be tied to VSS. 30/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 DC and AC parameters Table 12: Capacitance Symbol CIN COUT (3) tLP Parameter (1)(2) Min Max Unit Input capacitance - 7 pF Output capacitance - 10 pF Low-pass filter input time constant (SDA and SCL) - 50 ns Notes: (1) (2) (3) At 25°C, f = 1 MHz. Effective capacitance measured with power supply at 3.6 V; sampled only, not 100% tested. Outputs deselected. Table 13: DC characteristics Sym VCC (1) Parameter Test condition (2) Operating voltage Min Typ ICC2 Supply current 1.0 4.4 V I C bus (400 kHz) 1.3 4.4 V 100 µA 70 µA Supply current (standby) SCL = 400 kHz (no load) SCL = 0 Hz all inputs ≥ VCC – 0.2 V ≤ VSS + 0.2 V Unit Clock 2 4.4 V ICC1 Max 3.6 V 50 3.0 V 35 µA 2.5 V 30 µA 2.0 V 20 µA 4.4 V 950 nA 700 nA 3.6 V 375 3.0 V at 25 °C 350 nA 2.0 V at 25 °C 310 nA SQW off VIL Input low voltage –0.2 0.3 VCC V VIH Input high voltage 0.7 VCC VCC+0.3 V 0.4 V 0.4 V VOL Output low voltage VOH VCC = 4.4 V, IOL = 3.0 mA (SDA) VCC = 4.4 V, IOL = 1.0 mA (SQW, WDO, IRQ) Output high voltage VCC = 4.4 V, IOH = –1.0 mA (push-pull) Pull-up supply voltage (open drain) IRQ/OUT, IRQ/FT/OUT, 𝑊𝑊𝑊𝑊𝑊𝑊, SQW (M41T64 only) ILI Input leakage current ILO Output leakage current 2.4 V 4.4 V 0 V ≤ VIN ≤ VCC ±1 µA 0 V ≤ VOUT ≤ VCC ±1 µA Notes: (1) Valid for ambient operating temperature: TA = –40 to 85 °C; VCC = 1.3 V to 4.4 V (except where noted). (2) Oscillator startup guaranteed at 1.5 V only. DocID10397 Rev 21 31/45 DC and AC parameters M41T62, M41T64, M41T65 Table 14: Crystal electrical characteristics Sym fO Parameter (1)(2) Min Typ - 32.768 Resonant frequency RS Series resistance (TA = –40 to 70 °C, oscillator startup at 2.0 V) - CL Load capacitance - Max Units kHz 75 (3)(4) 6 kW pF Notes: (1) Load capacitors are integrated within the M41T6x. Circuit board layout considerations for the 32.768 kHz crystal of minimum trace lengths and isolation from RF generating signals should be taken into account. (2) For the QFN16 package, user-supplied external crystals are required. The 6 and 7 pF crystals listed in Table 15: "Crystals suitable for use with M41T6x series RTCs" have been evaluated by ST and have been found to be satisfactory for use with the M41T6x series RTC. (3) RS (max) = 65 kΩ for TA = –40 to 85 °C and oscillator startup at 1.5 V. (4) Guaranteed by design. Table 15: Crystals suitable for use with M41T6x series RTCs Manufacturer’s specifications Vendor Order number Citizen CMJ206T-32.768KDZB-UB Citizen CM315-32.768KDZY-UB max Temp. range (°C) Rated tolerance at 25 °C Rated load cap. 8.3 x 2.5 mm leaded SMT 50 kΩ –40/+85 ±20 ppm 6 pF 3.2 x 1.5 x 0.9 mm SMT 70 kΩ –40/+85 ±20 ppm 7 pF 2.0 x 6.0 mm thru-hole 50 kΩ –10/+60 ±20 ppm 6 pF 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF Package (1) ESR Ecliptek E4WCDA06-32.768K Ecliptek E5WSDC 07 - 32.768K ECS ECS-.327-6-17X-TR 3.8 x 8.5 x 2.5 mm SMT 50 kΩ –40/+85 ±20 ppm 6 pF ECS ECS-.327-7-34B-TR 3.2 x 1.5 x 0.9 mm SMT 70 kΩ –40/+85 ±20 ppm 7 pF ECS ECS-.327-7-38-TR 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF Epson MC-146 32.7680KA-AG: ROHS 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF Fox 298LF-0.032768-19 1.5 x 5.0 mm thru-hole 50 kΩ –20/+60 ±20 ppm 6 pF Fox 299LF-0.032768-37 2.0 x 6.0 mm thru-hole 50 kΩ –20/+60 ±20 ppm 6 pF Fox 414LF-0.032768-12 3.8 x 8.5 x 2.5 mm SMT 50 kΩ –40/+85 ±20 ppm 6 pF Fox 501LF-0.032768-5 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF Micro Crystal MS3V-T1R 32.768KHZ 7PF 20PPM 6.7 x 1.4 mm leaded SMT 65 kΩ –40/+85 ±20 ppm 7 pF Pletronics SM20S - 32.768K - 6pF 3.8 x 8.5 x 2.5 mm SMT 50 kΩ –40/+85 ±20 ppm 6 pF Seiko SSPT7F-7PF20PPM 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF Seiko VT200F-6PF20PPM 2.0 x 6.0 mm thru-hole 50 kΩ –10/+60 ±20 ppm 6 pF (2) Notes: (1) ST has been informed that this crystal has been terminated by the vendor. (2) Epson MC-146 32.7680KA-E: ROHS is 6 pF version. 32/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 DC and AC parameters Table 16: Oscillator characteristics Sym Parameter VSTA Oscillator start voltage tSTA Oscillator start time Cg XIN capacitance Cd Conditions Min ≤ 10 seconds 1.5 Typ Max Unit V VCC = 3.0 V 1 s 12 pF 12 XOUT capacitance IC-to-IC frequency variation (1)(2) –10 pF +10 ppm Notes: (1) Devices in LCC8 package ((M41T62LC6F) are tested not to exceed ±20 ppm oscillator frequency error at 25 °C, which equates to about 52 seconds per month. (2) Reference value. TA = 25 °C, VCC = 3.0 V, CMJ-145 (CL = 6 pF, 32,768 Hz) manufactured by Citizen, CL = Cg · Cd / (Cg + Cd). Figure 24: Bus timing requirements sequence SDA tBUF tHD:STA tHD:STA tR tF SCL tHIGH P tSU:DAT tHD:DAT tLOW S SR tSU:STA P tSU:STO Table 17: AC characteristics Sym Parameter (1) Min Max Units 0 400 kHz fSCL SCL clock frequency tLOW Clock low period 1.3 Clock high period 600 tHIGH µs ns tR SDA and SCL rise time 300 ns tF SDA and SCL fall time 300 ns tHD:STA START condition hold time (after this period the first clock pulse is generated) 600 ns tSU:STA START condition setup time (only relevant for a repeated start condition) 600 ns Data setup time 100 ns tHD:DAT Data hold time 0 µs tSU:STO STOP condition setup time 600 ns tBUF Time the bus must be free before a new transmission can start 1.3 µs trec Watchdog output pulse width 96 tSU:DAT (2) 98 ms Notes: (1) (2) Valid for ambient operating temperature: TA = –40 to 85 °C; VCC = 1.3 to 4.4 V (except where noted). Transmitter must internally provide a hold time to bridge the undefined region (300 ns max) of the falling edge of SCL. DocID10397 Rev 21 33/45 Package information 6 M41T62, M41T64, M41T65 Package information In order to meet environmental requirements, ST offers these devices in different grades of ® ® ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions and product status are available at: www.st.com. ® ECOPACK is an ST trademark. 34/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 6.1 Package information QFN16 package information Figure 25: QFN16 — 16-pin, quad, flat package, no-lead, 3x3 mm, package outline 7509604_4 Note: Drawing is not to scale. DocID10397 Rev 21 35/45 Package information M41T62, M41T64, M41T65 Table 18: QFN16 — 16-pin, quad, flat package, no-lead, 3x3 mm, package mechanical data mm inches Symbol Min Typ Max Min Typ Max A 0.80 0.90 1.00 0.032 0.035 0.039 A1 0.00 0.02 0.05 0.000 0.001 0.002 A3 b 0.20 0.18 D D2 1.55 36/45 0.007 1.70 1.55 1.70 1.80 0.061 0.30 0.012 0.067 0.071 0.118 1.80 0.061 0.40 0.008 0.50 0.20 0.010 0.118 3.00 e L 0.30 3.00 E E2 0.25 0.008 0.067 0.071 0.020 0.012 K 0.20 0.008 aaa 0.50 0.020 bbb 0.10 0.004 ccc 0.10 0.004 ddd 0.05 0.002 eee 0.08 0.003 DocID10397 Rev 21 0.016 M41T62, M41T64, M41T65 Package information Figure 26: QFN16 — 16-pin, quad, flat package, no-lead, 3 x 3 mm recommended footprint Note: Dimensions shown are in millimeters (mm). DocID10397 Rev 21 37/45 Package information 6.2 M41T62, M41T64, M41T65 LCC8 package information Figure 27: LCC8 — 8-pin, 1.5 x 3.2 mm leadless chip carrier package outline 8241725_2 Table 19: LCC8 — 8-pin, 1.5 x 3.2 mm leadless chip carrier package mechanical data mm inches Symbol Min Typ Min Typ b 0.30 0.40 0.50 0.012 0.016 0.020 D 1.40 1.50 1.60 0.055 0.059 0.063 D1 0.40 0.50 0.60 0.016 0.020 0.024 E 3.10 3.20 3.30 0.122 0.126 0.130 E1 2.20 2.30 2.40 0.087 0.091 0.094 e 0.80 0.90 1.00 0.032 0.035 0.039 L 0.32 0.42 0.52 0.013 0.017 0.020 A N 38/45 Max 0.80 8 DocID10397 Rev 21 Max 0.031 8 M41T62, M41T64, M41T65 Package information Figure 28: LCC8 — 8-pin, 1.5 x 3.2 mm leadless chip carrier recommended footprint 0.9 0.9 0.9 2.0 0.8 0.4 0.8 0.5 3.2 Note: Dimensions shown are typical values, in millimeters (mm). DocID10397 Rev 21 39/45 Packing information M41T62, M41T64, M41T65 7 Packing information 7.1 QFN16 carrier tape Figure 29: Carrier tape for QFN16 3 x 3 mm package P0 E P2 D T A0 F TOP COVER TAPE W B0 P1 CENTERLINES OFCAVITY K0 USER DIRECTION OF FEED Table 20: Carrier tape dimensions for QFN16 3 x 3 mm package Package W D E P0 P2 F A0 B0 K0 P1 T Unit Bulk qty QFN16 12.00 ±0.30 1.50 +0.10 /-0.00 1.75 ±0.10 4.00 ±0.10 2.00 ±0.10 5.50 ±0.05 3.30 ±0.10 3.30 ±0.10 1.10 ±0.10 8.00 ±0.10 0.30 ±0.05 mm 3000 40/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 LCC8 carrier tape 5.5 ±0.05 0.3 ±0.02 12 ±0.2 76 04 76 04 4 ±0.1 1.75 ±0.1 .1 Ø1 .5 ±0 2 ±0.1 Ø1 .5 ±0 4 ±0.1 .1 Figure 30: Carrier tape for LCC8 1.5 x 3.2 mm package 3.45 ±0.1 7.2 Packing information 1.75 ±0.1 User Direction of Feed Note: Dimensions shown are in millimeters (mm). DocID10397 Rev 21 41/45 Packing information 7.3 M41T62, M41T64, M41T65 Reel information for QFN16 and LCC8 Figure 31: Reel schematic T 40mm min. Access hole At slot location B D C N A G measured Tape slot In core for Full radius Tape start 2.5mm min.width At hub Table 21: Reel dimensions for 12 mm carrier tape - QFN16 and LCC8 packages A B (max) (min) QFN16 330 mm (13-inch) 1.5 mm LCC8 180 mm (7-inch) 1.5 mm Package D N (min) (min) 13 mm ± 0.2 mm 20.2 mm 60 mm 12.4 mm + 2/–0 mm 18.4 mm 13 mm ± 0.2 mm 20.2 mm 60 mm 12.4 mm + 2/–0 mm 18.4 mm C G T (max) Note: The dimensions given inTable 21: "Reel dimensions for 12 mm carrier tape - QFN16 and LCC8 packages" incorporate tolerances that cover all variations on critical parameters. 42/45 DocID10397 Rev 21 M41T62, M41T64, M41T65 8 Part numbering Part numbering Table 22: Ordering information scheme Example: M41T 62 Q 6 F Device family M41T Device type and supply voltage 62 = VCC = 1.3 V to 4.4 V 64 = VCC = 1.3 V to 4.4 V 65 = VCC = 1.3 V to 4.4 V Package Q = QFN16 (3 x 3 mm) LC = LCC8 (1.5 x 3.2 mm) (M41T62 only) Temperature range 6 = –40 °C to 85 °C Shipping method ® F = ECOPACK package, tape & reel For other options, or for more information on any aspect of this device, please contact the ST sales office nearest you. DocID10397 Rev 21 43/45 Revision history 9 M41T62, M41T64, M41T65 Revision history Table 23: Document revision history Date 21-Feb-2013 21-Aug-2015 44/45 Revision Changes 20 Updated title of datasheet; updated Section 3.8: "Century bits"; added Figure 21: "Century bits CB1 and CB0"; moved and modified Table 8: "Examples using century bits"; added Section 3.9: "Leap (1) year"; added footnote to Table 15: "Crystals suitable for use with M41T6x series RTCs". 21 Removed M41T63 part number and all references to it from document. Moved Table 1: "Device summary" to Section 1: "Description" Replaced Figure 10: "Hardware hookup for SuperCap™ backup operation" Updated Section 6.1: "QFN16 package information" Updated dimension e in Table 19: "LCC8 — 8-pin, 1.5 x 3.2 mm leadless chip carrier package mechanical data" DocID10397 Rev 21 M41T62, M41T64, M41T65 IMPORTANT NOTICE – PLEASE READ CAREFULLY STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order acknowledgement. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of Purchasers’ products. No license, express or implied, to any intellectual property right is granted by ST herein. Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product. ST and the ST logo are trademarks of ST. All other product or service names are the property of their respective owners. Information in this document supersedes and replaces information previously supplied in any prior versions of this document. © 2015 STMicroelectronics – All rights reserved DocID10397 Rev 21 45/45